You would want to do something clever with the data lines. If you are making the 'USB condom' for yourself, just short the data lines at the device end to enabl

You would want to do something clever with the data lines. If you are making the 'USB condom' for yourself, just short the data lines at the device end to enable fast charging (and be careful never to plug it into a computer.) If you're making it as a product, the thing to do is this: Have the 'USB condom' try to enumerate as a device, and request the maximum power draw possible, then offer the same to the chained USB device. If the 'USB condom' detects shorted data lines (meaning a fast charger), then short the downstream data lines to the device. You could probably sell these for a decent price, once this story gets out. :-)